Transcript Input and Output: The User Connection

Input and Output:
The User Connection
Chapter 5
Objectives
• Describe the user relationship with computer input
and output
• Explain how data is input to a computer system and
differentiate among various input equipment
• Describe how a monitor works and the characteristics
that determine quality
• List and describe the different methods of computer
output
• Differentiate among different kinds of printer
Explain the function of a computer terminal and
describe the types of terminals
Contents
• Input and Output
• Input
• Output
• Terminals
• Computer Graphics
• Ethics and Data
Input and Output
Input
• Users submit input data
Output
• Users get processed information
Input
• Data from the user
to the computer
• Converts raw data
into electronic form
Diversity of Input Methods
• Zebra-striped bar codes on supermarket items
• Word commands operate a forklift truck
• An order is entered using a pen on a special pad
• Time clock generates paycheck
• Data on checks are read and used to prepare a
monthly bank statement
• Charge-card transactions generate customer bills
Keyboard
• Traditional
– Looks like typewriter
with extra keys
• Non-traditional
– Fast food restaurants
– Each key represents a
food item rather than a
character
Keyboard
Function Keys
Main Keyboard
• Give commands
• Typewriter keys
• Software specific
• Special command keys
Keyboard
• Numeric Keys
– Num Lock – toggle
– On – numeric data & math symbols
– Off – cursor movement
• Cursor Movement Keys
Keyboard
Special Keys
Shift
Caps Lock
Ctrl
Alt
Esc
Enter
Windows
Shortcut
Pointing Devices
• Position a pointer / cursor on the screen
• Controls drawing instruments in graphics
applications
• Communicate commands to a program
Pointing Devices
Mouse
• Types
– Mechanical
– Optical
– Wireless
• Features
– Palm-sized
– 1 or 2 buttons
– Wheel
Other Pointing Devices
• Trackball
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Upside-down mouse
Ball on top
Roll ball with hand
Laptop computers
• Touchpad
– Pressure-sensitive pad
– Cursor moves as you
slide your finger
– Laptop computers
Other Pointing Devices
Pointing stick
• Pressure-sensitive post
• Mounted between G and H keys on keyboard
• Apply pressure in a direction to move cursor
Joystick
• Short lever
• Handgrip
• Distance and speed of movement control pointer
position
Graphics Tablet
• Digitizing tablet
• Rectangular board
• Invisible grid of electronic dots
• Write with stylus or puck
• Sends locations of electronic dots as stylus
moves over them
• Creates precise drawings
• Architects and engineers
Touch Screens
• Human points to a selection on the
screen
• Types
– Edges emit horizontal and vertical beams
of light that crisscross the screen
– Senses finger pressure
– Light pen for pointing
Touch Screens
• Kiosks
– Self-help stations
– Easy to use
– Where found
• Malls
• Disney World
• Government offices
Pen-based Computing
• Small hand-held devices
• Electronic pen (stylus)
– Pointer
– Handwritten input
• Personal Digital
Assistants (PDA)
Source Data Automation
• Special equipment to collect data at the
source
• Sent directly to a computer
• Avoids need to key data
• Related input areas
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Magnetic-Ink Character Recognition
Scanners
Optical recognition devices
Voice
MICR
Magnetic-Ink Character Recognition
• Read characters made
of magnetic particles
• Numbers on the
bottom of checks
• MICR inscriber – adds
characters to check
that show amount
cashed
Optical Scanners
• Optical recognition
• Light beam scans input data
• Most common type of source input
• Document imaging – converts paper documents to
electronic form
• Converts snapshots into images
• Converts scanned picture into characters – OCR
Exact computer-produced replica of original
Types of Scanners
• Flatbed
– One sheet at a time
– Scans bound documents
• Sheetfeed
– Motorized rollers
– Sheet moves across
scanning head
– Small, convenient size
– Less versatile than flatbed
– Prone to errors
Types of Scanners
• Handheld
– Least expensive
– Least accurate
– Portable
– User must move the scanner in a straight
line at a fixed rate
– Wide document causes problems
Optical Recognition
• Optical mark recognition (OMR)
– Mark sensing
– Exams
– Recognizes the location of the
marks
• Optical character recognition
(OCR)
– Light source reads special
characters
– OCR-A is ANSI standard typeface
for optical characters
Optical Recognition
Wand Reader
Retail stores
Libraries
Hospitals
Factories
Optical Recognition
Bar Code Reader
• Photoelectric device
• Reads bar codes
• Inexpensive
• Reliable
• Where Used?
– Supermarket – UPC
– Federal Express
Optical Recognition
Handwritten Characters
Must follow rigid rules
• Size
• Completeness
• Legibility
Voice Input
• Speech Recognition
• Speech recognition devices
– Input via a microphone
– Voice converted to binary code
• Problems
– Speaker-dependent
– Voice training
Voice Input
• Changing radio frequencies in airplane
cockpits
• Placing a call on a car phone
• Requesting stock-market quotations over
the phone
• Command from physically disabled users
Voice Input
• Discrete work systems
– Understand isolated words
– Pause between words
– Difficult for dictation
• Continuous work systems
– Normal speaking pattern
– Easy to use
– Faster and easier to dictate than to key
Digital Cameras
• Photos stored in electronic form
• No film
• Point and shoot
• Edit
Output
• Information for the user
• Types
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Screen – soft copy
Printer – hard copy
Voice
Sound
Graphics
Monitor
• Data that is entered appears on the
screen
• Screen is part of the monitor
Monitor
Cathode Ray Tube (CRT)
Flat panel display
Liquid Crystal Display (LCD)
CRT
Raster scanning
• Sweeping electron beams across the back of
the screen
• Phosphorous coating on back
• Glows when hit by a beam of electrons
• Phosphorous loses glow and image fades
and flickers
• Image must be continually refreshed
CRT
Refresh rate / scan rate
• Number of times electron beams refreshes
the screen
• 80-100 times per second adequate for clear
screen image
• Process also used for television
CRT
Interlaced vs. Non-interlaced
• Interlaced
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Refresh every other line on each pass
Lower refresh rate without flicker
Good for fixed graphics
Causes flutter with animated graphics
Inexpensive
• Non-interlaced
– Refresh every line on each pass
– Typical screen sold today
CRT
Color vs. Monochrome
• Color
– Typical monitor sold today
• Monochrome
– Green or amber on a contrasting
background
– Less expensive than color
CRT
Resolution
• Clarity of image
• Pixel (Picture element)
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Dot on screen
Is addressable
Can be illuminated
More pixels means higher resolution
• Dot pitch
– Distance between dots
– Smaller distance means better quality image
CRT
Graphics Card/Graphics Adapter Board
• Plugs into expansion slot on motherboard
• Graphics card and monitor must be
compatible for high quality image
CRT
Size
• Measured diagonally
• Typical sizes
– Office user: 15-17 inch
– High-powered graphics user: 19 inch
– High-end monitors: 21 inches and up
• Larger size
– More expensive
– More space on desktop
– Reduces eye strain
Graphics Standards
Help insure that the products work together
• PCs
• Monitor
• Graphics boards
• Software
Graphics Standards
• SVGA (Super VGA)
– Resolution – 800 x 600, 1024 x 768, 1280 x 1024,
1600 x 1200 pixels
– 16 million colors
– Number of colors displayed simultaneously limited
by amount of video memory
• XGA (Extended Graphics Array)
– High resolution
– Supports more simultaneous colors
– Allows non-interlaced monitors
Flat-panel Screens
• Liquid Crystal Display
(LCD)
• Primarily on laptops
• Moving to desktop
• Skinny (depth)
regardless of size
Flat-panel Screens
• Crisp, brilliant images
• Easy on eyes
• No flicker
• Full dimension is useable
• More expensive that CRT monitors
Flat-panel Screens
• Active Matrix
– Thin-film transistor technology (TFT)
– Transistors for each pixel
– Brighter image
– Viewable from an angle
• Passive Matrix
– Fewer transistors
– Cheaper
– Less power
Printer
• Produces information on paper
• Orientation
– Portrait
– Landscape
• Methods of printing
– Impact
– Nonimpact
Impact Printers
Line printer
Dot-matrix printer
One line at a time
One character
at a time
High volume
Low quality
Nonimpact Printer
Laser Printer
Nonimpact Printer
Laser Printer
• Transfers images to paper using a light beam
• Prints one page at a time
• 600-1200 dpi – High quality
• Speed
– Personal laser printers: 8-10 ppm
– Network laser printers: 35-50 ppm
– High-volume laser printers: up to 1000 ppm
• Black and white / color
Nonimpact Printer
Ink-jet Printer
• Spray ink at paper
• Black and white / color
• Excellent graphics
• Good quality
• Slower than laser
Nonimpact Printer
Choose based upon:
• Speed
• Quality
• Black and white vs. color
• Price
Sound
Creates multimedia output
Multiple sight and sound effects
Speakers
Sound card
Voice Output
Speech Synthesis
• Enables machines to talk to people
• Types
– Voice synthesizers
– Voice output devices
– Audio-response units
• Convert data in storage to vocalized sounds
• Synthesis by analysis – human sounds are stored
and reproduced as needed
• Synthesis by rule – creates artificial speech
Voice Output
Speech synthesis
Uses
• Automobiles
• Telephone surveys
• Catalog order is ready
• Your payment is late reminder
Music and Other Sounds
• MIDI (Musical Instrument Digital Interface)
– Communicates between MIDI devices and
computer
– Rules that produce and process digital music
signals
– MIDI information tells synthesizer
• When to start and stop playing a note
• Volume
• Modulation
• Software is available for composing and
editing per MIDI standard
Terminals
• Device that provides input and output capabilities
• Dumb terminal
– Keyboard and monitor
– Connects to host for processing
• Intelligent terminal
– Keyboard, monitor, memory, and processor
– Connects with host
• Point-of-sale terminal (POS)
– Input and output device
– Captures retail data
Computer Graphics
• Business
• Education
• Science
• Sports
• Computer art
• Entertainment
Business Graphics
• Types
– Maps
– Charts
• Help
– Compare data
– Spot trends
– Make decisions quickly
• Attention-getting
• Updated instantaneously
• Rendered quickly
Video Graphics
• Animated graphics
• Prepared one frame at
a time
• Examples
– Cartoons
– Commercials without
humans
– Television network’s logo
– Arcade games
CAD/CAM
Computer-Aided Design
Computer-Aided Manufacturing
• CAD
– Software creates 2-D and 3-D designs
• CAM
– Controls production equipment
• CIM (Computer Integrated Manufacturing)
– Bridge between design and manufacturing
– CAD/CAM integrated into manufacturing process
– Provides balanced, efficient production process
Ethics and Data
• Computer data can be
– Used
– Sold
– Altered
• What is legal?